Hydraulic control valves



March 1959 I F. H. TowLER ETAL 2,879,789

HYDRAULIC CONTROL VALVES Filed Feb. 9, 1953 //vv/v70/2 FRANK HATHORNEWLER JOHN MAURICETOWLER Y nrromevs United States PatentfO HYDRAULICCONTROL VALVES Frank Hathorn Towler, Rodley, and John Maurice Towler,Dob Park, near Otley, England; Frank H. Towler, administrator of saidJohn M. Towler, deceased Application February 9, 1953, Serial No.335,806

Claims priority, application Great Britain February 16, 1952 6 Claims.(Cl. 137-456) This invention relates to hydraulic control valves and, inparticular, to control valves for hydraulic presses in which theadmission and exhaust of primary pressure liquid to and from the presscylinders is controlled by pilot operated control valves and in whichthe pumps which supply the primary pressure liquid are provided withpilot-operated unloading valves. The invention is not restricted tohydraulic presses and it may be applied with equal facility to othermachines in which force is applied by hydraulic pressure.

One object of this invention is to provide a hydraulic emergency stopmechanism embodying a hydraulic control valve which may be closed byactuating a pushbutton and provided with additional means to close thevalve automatically if the pressure fails or falls below a predeterminedfigure and, when the valve has been closed by such emergency mechanism,it will remain closed until it has been reset by push-button. A furtherobject of this invention is to provide a hydraulic control valve ofimproved design embodying emergency mechanism such as described aboveand arranged so that, when it is closed, it interrupts the flow of pilotpressure to the pilot' control circuits.

The present invention consists broadly of a control valve which isoperable to control the flow of hydraulic pilot pressure liquid for theactuating of hydraulic apparatus in such manner that the valve member ofthe control valve is moved to the closed position either automaticallywhen the supply of pilot pressure liquid fails or is interrupted or itspressure falls below a predetermined figure or mechanically by manualactuation of a pushbutton, and is held in said closed position byautomatically operating means, and which is released and reset in theopen position by manual actuation of another push-button A control valveas above may have in combination a valve plunger against which the pilotpressure liquid can act to applya force tending to move the plunger toits open position and actuating means comprising two pivoted levers theinner ends of which co-act to. provide a cam and its follower, and theouter ends engaging respectively a push-button plunger which is springloaded and one end of the valve plunger, said spring automaticallyresisting opening movement of the valve plunger, and a furtherpush-button the inner end of which engages the inner end of one of thelevers so that the depressing inwards of the push-button will actthrough the levers to move the valve plunger to its closed position.

One embodiment of this invention is illustrated in the accompanyingdiagrammatic drawing by way of example, and comprises a control valveembodying emergency stop mechanism and comprises a valve body 1, valvespindle 2 with associated valve lever 3, actuated by the cam 4 andspring plunger 5, with a further emergency pushbutton plunger 6. Thevalve is shown in the open position in the drawing, with pilot pressureentering port 11 and passing out port 12 to the pilot circuit. Thepilotpressure operating on the area of the bottom of the spindle 2 tendsto hold the valve open in opposition to the spring 5 of the springplungerS. Overblow pressure from relief valves (not shown) in theprimary pressure system enter the valve at port 13, and act on theannular area of the piston 2 tending to close the valve in opposition tothe pilot pressure acting on the lower end of the spindle 2 Theintermediate portion of the valve between the piston 2 and the spindleend 2 is open to exhaust through the connection to the port 14. Thevalve lever 3 is pivoted intermediate its ends at 3 and has a roller 3which makes contact with the cam 4 which is pivoted at 4 The emergencypush-button 6 is held in contact with the cam by a light spring 6 Thespring 5 and plunger 5 tend to move the cam in a clockwise direction,looking at the drawing, in opposition to the pilot pressure acting onthe spindle end 2 which holds the lever 3 and roller 3 in contact withthe cam. The emergency push-button 6 may also serve to move the cam in aclockwise direction and close the valve. Thus the valve may be closed bythe emergency push-button 6 in opposition to the pilot pressure;alternatively, if the pilot pressure fails, the spring plunger 5 willclose the valve by means of the cam 4 and lever 3; or finally, bowotfpressure acting on the annular area of the piston 2 will close the valvein opposition to the pilot pressure and assisted by the spring plunger 5and spring 5 the spindle end 2 of the valve spindle being forced downinto the associated lapper bore 15 of the valve body, therebyinterrupting the flow of pilot pressure from the inlet port 11 to theoutlet port 12. When the valve has been closed by clockwise movement ofthe cam, by push-button 6, or by failure of pilot pressure, or byoverblow of primary pressure the valve will be held closed inconsequence of the relative positions of the cam and the roller 3 untilit is reset by the spring plunger 5 when actuated as a push-button andin this closed position of the valve the port 12 will be incommunication with the exhaust port 14.

What is claimed is:

1. In a control valve having a pressure fluid inlet port. and an outletport, the combination of a shiftable plunger controlling communicationbetween said ports, said plunger having an area at one end exposed tothe pressure prevailing at the inlet port urging the plunger toward openposition, afirsft lever pivoted intermediate its ends and having one endpositioned to engage the other end of the valve plunger and shift thesame axially, a second lever pivoted intermediate its ends for movementbetween operated and retracted positions, means operable man ually torock said second lever on its pivot relative to said first lever betweenoperated and retracted positions, and a cam surface onone of the leversco-operatingwith afollow'er on the other lever operative to rock said.first lever in a direction to'' shift" said plunger against the pressureexerted on said one end to closed position in response to the manualrocking of said second lever from a retracted position to an operatedposition, said cam surface being shaped to efiectively lock the leversagainst movement by the pressure applied to said one end of the plungerwhen the latter is in closed position.

2. In a control valve having a pressure fluid inlet port and an outletport, the combination of a shiftable plunger controlling communicationbetween said ports, said plunger having an area at one end exposed tothe pressure prevailing at the inlet port urging the plunger toward openposition, a first lever pivoted intermediate its ends and having one endpositioned to engage the other end of the valve plunger and shift thesame axially, a second lever pivoted intermediate its ends to swingbetween operated and retracted positions, and a cam surface on one ofthe levers co-operating with a follower on the

